This standard presser foot is a direct replacement for the Bernina 2500DCET overlocking machine.
Bernina 2500DCET Overlocker Standard Foot - Sewing Machines Ireland
Sew a scant 1/4" seam allowance. Red lines mark 1/4" and 1/8" pivot points in front of and behind the needle. Straight stitch, length 2.0-2.5mm.